Method and system for electric welding



Nov. 30, 1943.

F. H. ROBY METHOD'AND SYSTEM FOR ELECTRIC WELDING" Filed April 21, 1941 3 Sheets-Sheet 1 @&

INVENTOR W427 F Q- 3 Sheets-Sheet 2 INVENTOR l-l- F g-I.

' ATTO NEY F. H. ROBY METHOD AND SYSTEM FOR ELECTRIC WELDING Nov. 30, 1943.

Filed April 21, 1941 Nov. 30, 1943. F. a. ROBY 2,335,699

METHOD AND SYSTEM FOR ELECTRIC WELDING Filed April 21 1941 5 Sheets-Sheet 3 56 INVENTOR E AT ORNEY Fatented Nov. 30, 1943 12;, OFFICE METHUE AND SYSTEM FGR ELECTRIC WELDING Frank ll. Roby, Milwaukee, Wis,

assignor to Square It Company, Detroit Mich, a corporation oi Michigan Application April 21, 19;, Serial No. 389,548

1d Glaims.

This invention relate primarily to a method of and system for electric welding.

One object of the invention is to provide an improved, accurate and simplified method system of electric welding, providing tor delay, squeeze, weed, hold and on periods in a complete welding cycle.

Another object of the invention to provide a motor driven welding timer in which the motor is started for each single weld and for the first weld in a series of welds, in which provision is made for stopping the motor in a definite predetermined position of the timing device.

Another object of the invention is to provide a motor driven timing device in a welder control system, with a capacitor plugging arrangement to provide for positive positioning of the motor at rest,

Another object of the invention is to provide a welder control system utilizing a motor driven timer in which the timing period elapsing between the closing of the initiating control and the making of the first weld is substantially constant.

Another object of the invention is to provide a method and system of electric welding utilizing a motor driven timer in which a delay time, in addition to the squeeze time, is incorporated in each single welding cycle and in each initial cycle of a series of welding cycles.

Another object of the invention is to provide a new and improved method and system of plugging or braking alternating current motors.

Other objects and features of the invention will be readily apparent to those killed in the art from the specification and appended draw ings illustrating certain preferred embodiments in which: 1

Figure l is a front elevational view of a control panel for the method and system according to the present invention.

Figure 2 is a horizontal sectional view taken on the line 11-11 of Figure 1.

Figure 3 is a sectional view on the line I1IHI of Figure 1.

Figure 4 is a schematic representation of a welding machine on which the method and system of thi invention may be practiced.

Figure 5 is a view showingthe internal wiring diagram of the panel of Figure 1.

Figure 6 is a diagrammatic view of the wiring connections and equipment exterior to the panel of Figure 5. v

Figure '7 is a simplified schematic wiring diagram.

Figure 8 is a circle diagram showing points of contact operation.

reactor 5, a control transformer 6, a pair of electromagnetically operated electric switches I and 8, and a plugging condenser 53.

The timing switch 2 shown more particularly in Figures 1, 2 and 3, comprises a pair of stationary supporting members ii and I! having central hubs containing hearings in which is rotatably disposed the operating shaft l3 upon which are mounted the contact operating cams l4, l5 l6, ll, l8, l9, and 2|. On opposite sides of the stationary supports H and i2 are rotatably mounted the contact supporting plates 22, 23, 26' and 25, these plates being normally held stationary by the spring clips indicated at 25, but being rotatable by means of handle elements 21 rigidly mounted on the plates that their relation with respect to the operating shaft 13 and the cams may be adjusted. Upon each of the plates 22, 23, 24 and 25 are pivotally mounted contact arms 28 biased by springs 29 toward contacts engaged position. Contact arms 28 carry movable contact 3i adapted to cooperate with stationary contacts 32 on the plates. The contact arms 28 carry rollers 33 which engage their respective cams to efiect rotation of the contact arms to effect engagement and disengagement of th cooperating contacts 3| and 32. The shaft i3 is driven through gearing 34 and through a reduction gear mechanism incorporated in. the motor 3 and the speed of rotation of the shaft l3, and hence the speed to the welding cycle may be varied by changing the gearing 34, a suitable group of interchangeable gear elements being provided on the panel at 35. The movable contact on plate 24 has been indicated at iii. A similar movable contact on plate 22 is indicated at 36 and the movable contacts on plates 23 and 25 are indicated at 37 and 38 respectively. At the left hand end of shaft 13 and cooperating with the in ulating cam elements l4, l5 and I6 are three relatively light sets or" contacts 39, M and 42. The contact sets 39 and 42 are formed to be closed on the high part of the cam and contact set M is formed to be open on the high part of the cam. The points of operation of the cams l4, l5 and it may be determined by varying their tacts 45, 46 and 41 shown in the Figures 5 8.11117.

The electromagnetic switch or relay 8 comprises an operating coil 48 and four sets of cooperating contacts, two of the sets, 49 and 5|, being normally closed and two sets, 52 and 53, being normally open.

Figure 4 shows a schematic diagram of a weldlng tool or machine on which the method and system may be practiced. This comprises a frame 64 having an operating cylinder 55 within which is piston 56 carrying a movable electrode 61. A stationary electrode 58 is supported in the frame through an insulating bushing 59, power being let to the electrodes through conductors 6| from the secondary of the welder transformer, not here shown. The movements of the piston 56 are controlled through a solenoid valve which comprises an operating winding 62 and a slide 63. A source of fluid pressure 64 is provided,

. controlled by the solenoid valve to determine the position of the upper electrode. In the position shown in Figure 4, the coil 62 has just been deenergized so that the source of fluid pressure has now been connected to the under side of the piston whereupon the movable electrode will move upwardly to release the work as at the completion of a welding cycle.

In the external wiring diagram of Figure 6, in addition to the parts previously described, there are shown a push button control switch 65, a welding transformer 66, and a contactor in the primary of the welding transformer circuit which includes an operating coil 61 and cooperating contacts 66. Associated with this contactor is a synchronizing feature supplied by the auxiliary synchronizing coil 69 energized by the secondary of a transformer 1| in whose primary circuit is an adjustable resistor 12, adjustment of the resistor i2 determining the point on the supply wave at which the contacts separate, this contacto'r' synchronization being more fully described and claimed in the copending application of Ernest G. Anger, Serial No. 204,052 filed April 25, 1938, for Electric switch, now Patent No. 2,273,311, dated Feb. 1'7, 1942.

Figure 8 is a circle diagram representing the points of actuation of the contacts which may be utilized in the operation of the method and system. It is understood that all of the contacts are adjustable in that either their mounting plates and/or their operating cams are adjustable with respect to the shaft i3. In the ordinary operation of the system, however, only the contacts 31, 3| and 38 and 39 will require adjustment, the contacts 4|, 32 and 36 having a relatively fixed setting. The system provides a constant point of rest for the operating motor and timing switch, which constant stop point has been indicated at H on the circle diagram of contact operation.

. The other points indicated on this diagram are as follows: point A where contact 31 opens; point B at which contact 42 opens; point C at which contact 36 closes; point D at which contact 4| closes; point E at which contact 39 opens; point aesaeee F at which contact 3| closes and point G at which contact 38 opens. The points at which the alternative contact operations occur, i. e. the opening points for the contacts herein referred to as closing and the closing point for the contacts referred to as opening, do not affect the operation of the system,

To initiate a welding cycle after the work has been placed between the electrodes, the operator presses the push button starting switch 66. This may be only momentarily closed for a single weld, or the .push button may be maintained closed to effect a plurality of welds in a series. Upon the closing of the push button switch 65, the operating coil 43 of the relay or-switch l is immediately energized, closing its contacts 66, 46, and 41 and opening contact 44. The closing of contact 41 forms a holding circuit for the operating coil 33 through the normally closed contact 49 of relay or switch 6. The closing of contact 46 immediately energizes the operating coil 52 of the solenoid valve through the normally closed contact 5| of the relay 8. When the coil 62 is energized, the solenoid valve operates to apply pressure to the upper side of the piston 56 diagrammatically shown in Figure 4, whereupon the movable electrode 51 descends to apply pressure to the work. The closing of contact 45 energizes the synchronous motor 3 which then accelerates to its full operating-speed. The opening of contact 44 disconnects the circuit through the plugging condenser 9 to disconnect it from around the motor 3 during the normal operation of the system.

The operating shaft l3 of the motor driven timing switch 2 rotates from the position-of point H, which was taken as the rest point of the shaft, to the first point reached at A where contact 31 opens. This, however, has no effect in single welds and in the first of a series of welds, since the holding circuit about contact 31 is still provided by the normally closed contact 5| of relay 8. It is this normally closed contact which effects the additional delay time which is added to the normal "squeeze time in single welds and in the first of aseries of welds, as will be explained hereinafter. The cam shaft |3 continues to rotate until point B is reached, at which point contact 42 opens, again without effect since coil 43 is energized throughthe normallyclosed contact 49 of relay 8. The cam shaft continues to rotate to point C at which contact 36 closes but again without effect since the solenoid valve is already energized through the normally closed contact 5|. At the next point D contact 4| closes to effect energization of the operating coil 48 of the relay 6- through the now closed of relay 1,

Relay 8 is energized to effect opening of contacts 49 and 5| and closing of contacts 52 and 53. The closing of contact 53 forms a holding circuit for contact 58 around the cam operated contact 4|. The opening of contact 5| opens the holding circuit about contacts and 31 to the solenoid valve 62 and new places the control of the solenoid valve in the parallel connected, cam operated contacts 36 and 31. The opening of contact 49 removes the holding circuit around the cam operated contact 42 and places the. control of the operating coil 43 in cam driverr 'contact 42 when the push button 65 is released; The closing of contact 52 sets up the circuit to the operating coil 61 for the contacts 68 in the circuit to the primary of the welding transformer. As the cam shaft l3 continues to rotate, at point contact 46 assascc E the contact 39 is opened, but without effect,

- since it is short circuited by the now closed contact 45. .At point F in the rotation of the cam shalt, contact 3i closes and this effects energization of the operating coil ill to close the contact 8&3, and energizes the welding transformer to start the flow of current through the weld. The current continues to flow until point G is reached, at which point contact 33 opens to deenergize the coil 3? and efiect opening of contact 33. a Syncro-break contactor is employed of the disclosed in application Serial No. 952 aforesaid, the opening point of the contact will be further controlled by the adjustment of the cur rent in the auxiliary synchronizing coil fill. interruption of the current completes the weld period in the welding cycle. As the shaft con tirluesto rotate, the point A is again reached and now the opening of contact Ill effects deenergizetion of the operating coil of the and removes the pressure on the welding elec trode to release the work,

If the push button has been maintained depressed, the. shaft continues to rotate without operation in the system until point C is reached when contact closes to again energize the operating coil 62 of the solenoid valve and re= establish welding pressure on the worls. At points F and G, the welding current is applied and interrupted, and at point A the pressure is again released. This repetition of sequential pressure and current application and release is carried out to make successive welds in a series of welds so long as the push button is remained. depressed.

Whenever the push button is released, either at the end of a series or after being momentarily closed for a. single Weld, the operations previ ously described take place and when the cam shaft reache's point B after "the push button is released (and at least one weld completed) the opening of contact d2 effects cleenergization of the operating coil ill of the relay 5. The deener-= gization of this relay eifects closing of contact id and opening of contacts 35 and ll. The opening of contact 46 effects opening of the cincuit to the solenoid valve 62 and deenergiaes the operating coil 38 of relay 3 whose deenergization effects opening of contacts 52 and and clos ing of contacts t9 and ill. The'opening of contact l5 places the control of the motor circuit in the cam operated contacts lhe closing of contact ill again closes the circuit to the plugging condenser which is now connected in parallel with the motor winding. The opening of con tact 52 opens the circuit to the welder contactor and prevents closing thereof as the cam shaft continues to rotate. After the operations just described, points C and D are passed in the rotation of the shaft without efiecting operation of the elements of the system, since the circuit thereto is open at contact ll At the point E contact 35 is opened. This disconnects the motor from the line and permits the condenser ii to discharge through the motor winding. This condenser discharge effects a very quick stopping of the motor and at the same predetermined point, such as the point H indicated on the circle diagram on Figure 8. The system is now at rest and is prepared for the initiation of a new welding cycle.

The positioning motor at rest at a predetermined point in the rotation of the cam shaft provides obvious advantages in the system, since it is unnecessary to have the motor rotate consolenoid valve have an initiating up at one point in stantly and unnecessary to relay which would be picked the operation of the shaft. Furthermore, the positive position of the motor at rest makes the total elapsed time between the closing of the push button and the making of the first weld become constant. This positive positioning further provides a definite delay time for single welds and. the first weld in a series of welds.

plugging or braking b0 definite predetermined position is very efficiently effected by the use or" the plugging condenser which feeds back or discharges through the motor wirulin to effect the quiet: stopping thereof. For most efficient operation, it is desired to have the condenser charge to brake the motor when the maximum energy is stored. therein. It is further desirable this charge on the condenser for brah be maintained constant to avoid the possibi.1- of variable braking which would occur if the motor and condenser were disconnected from the line at some point other than current zero. Since the contact is synchronously driven, the ad justinent of cam operator with respect to the shaft ill may be set so as to insure opening of the contacts when the current therethrough has an instantaneous value of zero. To further effect this interruption of the motor circuit when the current is zero, the reactor .5 is placed in series with the condenser so that should the contacts actually separate at a point other than current zero, through misadjustment thereof, the inductance in the circuit provided by the reactor 5 will cause arcing at the contact tips to pass current until the arc is interrupted at the zero point of the current cycle. Accordingly, it is seen that the condenser and motor circuit will be interrupted, either through the accurate positioning of the contact operating cam or by the arcing at the contacts, when the current has an instantaneous value of'zero and a substantially constant and maximum charge on the condenser will be used to effect constant braking of the driving motor.

Again referring to the circle diagram of Figure 8, the portion of the rotation of the cam shaft l represented by the are between point H and point C represents the delay time during which the pressure is building up on the wort: and which is utilized only for single welds and for the first in a series of welds. This additional time adds on to the squeeze time normally provided for each weld in a continuous series of welds. The desire for this additional time for single and initial welds is necessitated by various factors such as additional friction in the welding tool, a greater movement of parts, and

other reasons which require a longer time to build up adequate welding pressure after the solenoid valve is energized after the system is at rest. This additional delay time is provided through the normally closed contact 55 of relay 8 which permits energization of the operating 'coil of the solenoid valve immediately the contact 43 closes, which closing is elfected when the push button is initially closed. However, contact 5i being opened when relay 8 is energized, places thecontrol of the solenoid valve, so long as relay remains energized, in the contacts 38 and 3?? so that after the first weld in a continuone series of welds is completed, the solenoid valve will therefore be energized only at the point C in the welding cycle so that the delay" time does not occur in other than in single welds or in the first of a series of welds. In all welds,

a squeeze time represented by the are between points C and F is provided. In the case of single welds and the first in a series of welds, this time is simply added to the delay time represented by the arc H-C so that the total time between energization of the solenoid valve and application of current is represented by the long are HF for single welds and the first in a series of welds. The weld time in the welding cycle is represented by the arc F-G during which the welding transformer primary is energized to pass current through the work. The "hold time in the welding cycle is represented by the arc G-A in which the pressure on the electrodes is maintained after current hasceased to flow. The ofF' time in the welding cycle where a continuous series of welding cycles is being efiected is represented by the arc AC in which pressure is released.

In the circle diagram of Figure 8 it is seen that points 13, C and D are relatively constant and need not ordinarily be adjusted after the factory adjustment of the timing switch. However, points E, F, G and A are made readily adjustable on the timing switch, since the relation of point F with respect to point C determines the squeeze time and the relation of point G with respect to point F determines the weld time, 'and the relation of point A with respect to point G determines the hold time; also, the relation of point E deterthe minimum time required for the motor to accelerate the synchronous speed. The adjustment of points F, G and H is efiected by move-- ment of the handles 2'! which rotate contacts 3!, 38 and 31 with respect to the operating cam shaft and hence determine the points at which contact operation is efiected. The adjustment of point E may be effected by changing the position of cam 14 on the cam shaft l3.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims:

What is claimed is:

1. A method of operating upon a work circuit which comprises closing an initiating switch, energizing an electric relay when said initiating switch is closed, energizing a fluid pressure control means to establish a work circuit and the driving motor of a motor driven timing switch when said relay is energized, energizing a second relay when said timing switch rotates to a predetermined position, placing the control of the'energization of the fluid pressure control means in the contacts of said timing switch when said second relay is energized, energizing and deenergizing said work circuit to pass current therethrough in predetermined positions of the timing switch, deenergizing the fluid pressure control means in another predetermined position of the timing switch, deenergizing said first relay in another predetermined position of the timing switch provided the initiating switch has, in the meantime, been opened, deenergizing the second relay when. the first relay is deenergized, and deenergizing the driving motor of said timing switch in another predetermined position of said timing switch.

2. A method ofoperating upon a work circuit which comprises closing an initiating switch. en-

ergizing an electric relay when said inititating switch is closed, energizing a fluid pressure control to establish a work circuit and the driving motor of a motor driven timing switch when said relay is energized, energizing a second relay when said timing switch moves to a predetermined position, placing the control of the energization of the fluid pressure control means in the contacts of said timing switch when said second relay is energized, energizing and deenergizing said work circuit to pass current therethrough in predetermined positions of the timing switch, deenergizing the fluid pressure control means in another predeter-mined position of the timing switch, deenergizing said first relay in another predetermined position of the timing switch provided the initiating switch has, in the meantime, been opened,deenergizing the second relay when the first relay is deenergized, deenergizing the,

driving motor of said timing switch in another predetermined position of said timing switch, and braking said driving motor and timing switch to a stop in a predetermined position thereof.

3. A method of operating upon a work circuit which comprises closing an initiating switch, energizing an electric relay when said initiating switch is closed, energizing a fluid pressure control means to establish a work circuit and the driving motor of a motor driven timing switch when said relay is energized, energizing a second relay when said timing switch moves to a predetermined position, placing the control of the energization of the fluid pressure control means in the contacts of said timing switch when said second relay is energized, energizing and deenergizing said work circuit to pass current therethrough inpredetermined positions of the timing switch, deenergizing the fluid pressure control means in another predetermined position of the timing switch, deenergizing said first relay in another predetermined position of the timing switch provided the initiating switch has, in the meantime, been opened, deenergizing the second relay when the first relay is deenergized, deenergizing the driving motor of said timing switch in another predetermined position of the timing switch, and discharging a condenser through windings of the driving motor so as to brake the timing switch to a stop in a predetermined position.

4. A method of operating upon a work circuit which comprises closing an initiating switch, energizing an electric relay when said initiating switch is closed, energizing a fluid pressure control means to establish a Work circuit and the driving motor of a motor driven timing switch when said relay is energized, energizing a second relay when said timing switch moves to a predetermined position, placing the control of the energization of the fluid pressure control means in the contacts of said timing switch when said second relay is energized, energizing and deenergizing said' work circuit to pass current therethrough in predetermined positions of the timing switch, deenergizing the fluid pressure control means in another predetermined position of the timing switch, deenergizing said first relay in another predetermined position of the timing switch provided the initiating switch has, in the meantime, been opened, deenergizing the second relay when the first relay is deenergized, deenergizing the driving motor of the timing switch in another predetermined position of said timing switch, connecting a condenser in parallel with the windings of said driving motor prior to the interruption of the circuit therethrough, and discharging the said predetermined 3 switch, en said initiating is closed, energizing a tad pressure contrc means to establish a work circuit and the motor of a motor driven timing switch n said relay is energized, energizing a second y when said timing switch moves to a preden-ed position, placing the control of the energ ation of the fluid pressure control means in the contacts of said timing switch when said sec relay is energized, energizing and deerkrgis t said work circuit to pass current therethrough predetermined positions of timing switch, deenergizing the fluid pressure control means in or pred termined position of the timi 5 switch, deenergizlng said first relay in another predetermined position of the timing switch proded the initiating switch has, in the meantime, en opened, deenergizing the second relay when motor of the timing sw determined position of in another motor driven ch, connecting a condenser in parallel with motor windings, interrupting the motor circuit when current therethrough an instantaneous value of substantially zero to effect a in rnum charge on the condenser, and dissaid condenser through the motor windto brake the motor driven switch to a stop in a predetermined position.

s. A method of operating upon a work circuit which comprises closing an initiating switch, energizing an electric relay when said initiating switch is closed, energizing a fluid pressure con trol means to establish a work circuit and the driving motor of a motor driven timing switch when said relay is energized, energizing a second relay when said timing switch moves to a predetermined position, placing the control of the energization of the fluid pressure control means in the contacts of said. timing switch when said second relay is energized, energizing and deenergizing said work circuit to pass current there-through in predetermined positions of the timing switch, deenergizing the fluid pressure control means in another predetermined position of the timing switch, continuing to initiate and reiease pressure and pass current through the work circuit in predetermined sequence so long as said initiating means remains closed and without cleenergizing said relays, deenergizing said first relay in another predetermined position of the timing switch providing the initiating switch has, in the meantime, been opened, deenergizing the second relay when the first relay is deenergized, and deenergizing the driving motor of the timing switch in another predetermined position of said timing switch.

'7. The steps in a method of electric welding to secure a constant delay time added to the squeeze time in the case of single welds and in the first of a series of Welds which comprises starting a motor driven timing switch from a predetermined position to initiate a weld and energizing fluid pressure electrode control means when the motor driven switch is started independent of the contacts of the motor driven switch in the case of single welds and the first weld of a series, thereafter controlling the squeeze period in the welding cycle solely by he first relay is deenergized, d energizing the the contacts motor driven switch s delay period in wseries, and. stopping s in a ,redetei 5 bl. at" series or welds so that locate-c for applica i clay period the next a cycle.

control 1 1d rol means timing placin pred said

passing curren pie errnined "oer" v v1. .l rgization predetermined pt n of ress and passage 1' en 1 under motor driven sequence to perform of welds as long as the ini s ctuated, m ediate pressure control means itch is actuated, prior to ing switch contacts which co och one: V on in a continuous series, A provone an add onal delay time added to the r Mal squeez time in the welding cycle in the case of ingle welds and weld in a series of welds.

" welder c ntrol system for electrically orir passing current therethrough electrodes pressed against the wort: by sure, motor driven timing switch havof sequentially operated contact g switch, means controlling the aid pressure, means im "teiy starting said motor and energizing said press re of control n cans independently contacts of the timing switch when the switch is actuated, means placing or the energization of the pressure means in the contacts of said timing switch when the switch is in a predetermined position, means controlled by contacts on said timing switch for current through the weld dur ng a predetermined period of movement of the rning switch, said timing switch discontinuing the energization of the fiuid pressure control means in another predetermined position, the application of pressure and passage of current being hereafter entirely under the control of the contacts of the timing switch and continuing in sequence to perform a continuous series of welds as long as the initiating switch remains actuated, the immediate energization of the fiuici pressure control means when the initiating switch is actuated, prior to the actuation of the timing switch contacts which control such energization in a continuous series, providing a additional delay squeeze of single welds and the first weld in a series of welds, means for deenergizing the control system when the last weld in a series has been completed, the deenergization of the system afiecting return of said means which places the control of the fluid pressure control means in the contacts or the timing switch into a position where the control of the energlzation of the fluid pressure control means is again eifected independently of the contacts of the timing switch when the initiating switch is actuated.

10. In a welder control system for electrically welding work by passing current therethrough between electrodes pressed against the work by fluid pressure, a motor driven timing switch having a plurality of sequentially operated contact sets, an initiating switch, means controlling the application of the fluid pressure, means for immediately starting said motor and energizing said fluid pressure control 'means independently of the contacts of the timing switch when the initiating switch is actuated, means placing the control of the energization of the fluid pressure control means in the contacts of said timing switch when the switch is in a predetermined position, means controlled by contacts on said timing switch for passing current through the weld during a predetermined period of movement of the timing switch, said timing switch discontinuing the energization of the fluid pressure control means in another predetermined position, the application of pressure and passage of current being thereafter entirely under the control of the contacts of the timing switch and continu ing in sequence to perform a continuous series of welds as long as the initiating switch remains actuated, the immediate energization of the fluid pressure control means when the initiating switch is actuated, prior to the actuation of the timing switch contacts which control such energization in a continuous series, providing an additional delay time added to the normal squeeze time in the welding cycle in the case of single welds and the first weld in a series of welds, means for deenergizing the control system when the last weld in a series has been completed, and means for stoppin said timing switch in a predetermined position so that the reenergization of the fluid pressure control means independently of the contacts of the timing switch when the initiating switch is again actuated will be efifected when the timing switch is in a predetermined position.

11. In a welder control system for electrically welding work by passing current therethrough between electrodes pressed against the work, a motor driven timing switch incorporating a plurality of sets of main contacts and at least three auxiliary sets of contacts, a pair of relays, an initiating switch, means for energizing one of said relays when said initiating switch is actuated, means for initiating welding pressure and for starting the motor driven timing switch when said first relay is closed, means for energizing the second relay through one of said auxiliary contacts in a predetermined position of the timing switch, means for starting and stopping the passage of current through the weld unde" the control of certain of said main contacts in a predetermined position of said timing switch, means f or releasing the electrode pressure under the control of certain of said main contacts in another predetermined position of the timing switch, means for deenergizing said first relay by a second of said auxiliary contacts in a predetermined position of the timing switch, deenergization of said first relay effecting the deenergization of said second relay, and means for disconnecting the motor circuit through the third of said auxiliary contacts in another predetermined position of the timing switch.

12. In a welder control system for electrically welding work by passing current therethrough between electrodes pressed against the work, a motor driven timing switch incorporating a plurality of sets of main contacts and at least three auxiliary sets of contacts, a pair of relays, an

, initiating switch, means for energizing one of said relays when said initiating switch is actuated, means for initiating welding pressure and for starting the motor driven timing switch when said first relay is closed, means for energizing the second relay through one of said auxiliary contacts in a predetermined position of the timing switch, means for starting and stopping the passage of current through the weld under the control of certain of said main contacts in a predetermined position of said timing switch, means for releasing the electrode pressure under the control of certain of said main contacts in another predetermined position of the timing switch, means for deenergizing said first relay by a second of said auxiliary contacts in a predetermined position of the timing switch, deenergizatlon of said first relay effecting the deenergization of said second relay, means for disconnecting the motor circuit through the third of said auxiliarycontacts in another predetermined position of the timing switch, and means for braking the timing switch to a stop in a predetermined position. v

13. In a welder control system for electrically welding work by passing current therethrough between electrodes pressed against the work, a motor driven timing switch incorporating a plurality of sets of main contacts and at least three auxiliary, sets of contacts, a pair of relays, an initiating switch, means for energizing one of said relays when said initiating switch is actuated, means for initiating welding pressure and for starting the motor driven timing switch when said first relay is.closed, means for energizing the second relay through one of said auxiliary contacts in a predetermined position of the timing switch, means for starting and stopping the passage of current through the weld under the ,control of certain of said main contacts in a predetermined position of said timing switch,

means for releasing the electrode pressure under the control of certain of said main contacts in another predetermined position of the timing switch, means for deenergizing said first relay by a second of said auxiliary contactsin a predetermined position of the timing switch, but only if said initiating means has been opened, deenergization of said first relay effecting deenergization of said second relay, means for disconnecting the motor circuit through the third of said auxiliary contacts in another predetermined position of the timing switch, but only if 2,885,699 and the successive operations thereafter will be effected when, the timing switch is in predetermined positions after such openingv of the initiating means.

14. In a welder control system for electrically welding work by passing current therethrough between electrodes pressed against the work, means controlling the application and release of pressure to the electrodes, means controlling the passage of current through the work, a. timing switch having at least four sequentially operated sets of contacts thereon, means connecting two of said sets of contacts in parallel to control the energization of the means controlling the application and release of pressure whereby said means controlling the application and release of pressure will remain energized while either of said two sets of contacts are closed, and means connecting two other sets of said contacts in series and to control passage of current through the work whereby current will flow only in the overlapped period in which both of said last two sets of said contacts are closed.

' FRANK H. ROBY. 

